Water Permeation through Elastomers and Plastics

1983 ◽  
Vol 56 (3) ◽  
pp. 594-618 ◽  
Author(s):  
Patrick E. Cassidy ◽  
Tejraj M. Aminabhavi ◽  
Corley M. Thompson
Keyword(s):  
Protective Coatings ◽  
Polymer Structure ◽  
Artificial Kidney ◽  
Published Data ◽  
Potential Importance ◽  
Dormant Period ◽  
Water Permeation ◽  
Ultimate Properties ◽  
Successful Design ◽  
Reverse Osmosis Desalination

Abstract The available data on permeability, diffusivity, and solubility of water and water vapor through elastomers and plastics have been summarized. In many ways, the last five years have been a relatively dormant period, following the previous fifteen years when most theories and experimental data were generated. From a practical and technical viewpoint, knowledge of permeation, diffusion, and solution behavior is essential for the successful design and use of many products, such as packaging films and other protective coatings. This knowledge had an immediate impact on the development of efficient permselective membranes to satisfy the exacting conditions required for use as media for reverse osmosis desalination, artificial kidney and lung components, and for other precise separations of multicomponent penetrant mixtures. The interdependence of polymer structure and transport behavior—a major factor affecting the ultimate properties of films and membranes—is of increasing importance as our ability to control polymer synthesis and characterize polymer structure has become more precise and predictable. It is to be expected that even more dramatic progress in membrane technology will result from the ever quickening pace of research in related areas of science spurred on by the increased awareness of the present and potential importance of membrane phenomena. There are two serious and pandemic problems which plague researchers in the field of transport of water through elastomers and plastics. One of these is that a variety of techniques are used to measure permeability that cannot be compared to one another. The second is that the composition of the membrane is often not reported precisely in the published data.

scholarly journals The fatty acids based organofunctional silane protective coatings for concrete

2021 ◽  
Vol 71 (341) ◽  
pp. e238
Author(s):  
K. Szubert
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Free Fatty Acids ◽  
Protective Coatings ◽  
Concrete Surface ◽  
Water Permeation ◽  
Hydrophobic Character ◽  
Organofunctional Silanes ◽  
Oil Paints ◽  
Derivatives Of

The possibility of using free fatty acids for the synthesis of new organofunctional silanes is shown. In nature, fatty acids occur in the form of esters with glycerin (fats) and are widely used for production of soap, oil paints, medicines and cosmetics. Of particular interest in this study was the application of organosilicon derivatives of oleic acid for production of coating that would cover the surface of concrete and protect it from water permeation. As a result of proposed silanization, the concrete surface acquired hydrophobic character with the wetting angles up to 115°, and the concrete absorbability was reduced by up to 93%.

Coating Adhesion Effects on Fiber Strength and Fatigue Properties

1986 ◽  
Vol 88 ◽  
Author(s):  
Bolesh J. Skutnik ◽  
Barbara D. Munsey ◽  
Carol T. Brucker
Keyword(s):  
Water Absorption ◽  
Protective Coatings ◽  
Fiber Strength ◽  
Polymeric Materials ◽  
Fused Silica ◽  
Fatigue Properties ◽  
Static Fatigue ◽  
Strong Positive Correlation ◽  
Water Permeation ◽  
Lap Shear

ABSTRACTOrganic/polymeric materials remain the most prevalent protective coatings for optical fibers. Many studies have chronicled significant differences inn the levels of protection against moisture and other adverse environments by such coatings. Recently an attempt was made to identify those coating properties which correlate with these protective characteristics. Water absorption and adhesion between the coating and fused silica were proposed to correlate the best.In this study a series of coatings have been prepared with varying levels of adhesion to fused silica substrates, without significant differences in water absorption or in water permeation properties. The tensile strength, static fatigue and dynamic fatigue properties of the coated fibers were measured and correlated with the lap shear strengths of correspondingly coated slides. As the adhesion of the coating/silica glass interface increases, the corresponding fiber's strength and fatigue properties improve also.The strong positive correlation between the coating's adhesion and the fiber's strength/fatigue properties will be reported for a number of coating/fiber combinations. Effects on lifetime predictability will also be addressed.

A tilting high temperature gas reaction chamber for the JEM 7A T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 70-71
Author(s):  
Brian L. Rhoades
Keyword(s):  
Cross Section ◽  
Reaction Chamber ◽  
Objective Lens ◽  
Reduced Cross Section ◽  
Cross Sectional ◽  
Structural Investigations ◽  
Transmission Electron ◽  
Dynamic Experiments ◽  
Successful Design ◽  
Thermocouple Junction

A gas reaction chamber has been designed and constructed for the JEM 7A transmission electron microscope which is based on a notably successful design by Hashimoto et. al. but which provides specimen tilting facilities of ± 15° aboutany axis in the plane of the specimen.It has been difficult to provide tilting facilities on environmental chambers for 100 kV microscopes owing to the fundamental lack of available space within the objective lens and the scope of structural investigations possible during dynamic experiments has been limited with previous specimen chambers not possessing this facility.A cross sectional diagram of the specimen chamber is shown in figure 1. The specimen is placed on a platinum ribbon which is mounted on a mica ring of the type shown in figure 2. The ribbon is heated by direct current, and a thermocouple junction spot welded to the section of the ribbon of reduced cross section enables temperature measurement at the point where localised heating occurs.

A Biological Cryosystem for the Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 414-415
Author(s):  
Zhang zhaohua ◽  
Luo Dong ◽  
Guo Yisong
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Natural State ◽  
Specimen Preparation ◽  
Cold Stage ◽  
Specimen Temperature ◽  
Successful Design ◽  
Scanning Electron

Since early 1970's the use of cold stage on SEM for observation of hydrated samples in their natural state has become more and more popular despite its high cost. Experiences gained from earlier experiments indicate that a successful design should incorporate thefollowing features:1. The specimen temperature should be below −135°C (the recrystallization point of water), lower the temperature, better the results.2. The frozen specimen, the cold block in the specimen preparation chamber, as well as the cold stage should be kept under vacuum at all times to keep them frost free.3. Different specimen preparation processes such as fracturing, coating and sublimation should be possible in one compact preparation chamber .

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

Metallic prions

2004 ◽  
Vol 71 ◽  
pp. 193-202 ◽  
Author(s):  
David R Brown
Keyword(s):  
Prion Protein ◽  
Binding Capacity ◽  
Normal Function ◽  
Transmissible Spongiform Encephalopathies ◽  
Published Data ◽  
Normal Brain ◽  
Copper Binding ◽  
Loss Of Function ◽  
Spongiform Encephalopathies ◽  
The Brain

Prion diseases, also referred to as transmissible spongiform encephalopathies, are characterized by the deposition of an abnormal isoform of the prion protein in the brain. However, this aggregated, fibrillar, amyloid protein, termed PrPSc, is an altered conformer of a normal brain glycoprotein, PrPc. Understanding the nature of the normal cellular isoform of the prion protein is considered essential to understanding the conversion process that generates PrPSc. To this end much work has focused on elucidation of the normal function and activity of PrPc. Substantial evidence supports the notion that PrPc is a copper-binding protein. In conversion to the abnormal isoform, this Cu-binding activity is lost. Instead, there are some suggestions that the protein might bind other metals such as Mn or Zn. PrPc functions currently under investigation include the possibility that the protein is involved in signal transduction, cell adhesion, Cu transport and resistance to oxidative stress. Of these possibilities, only a role in Cu transport and its action as an antioxidant take into consideration PrPc's Cu-binding capacity. There are also more published data supporting these two functions. There is strong evidence that during the course of prion disease, there is a loss of function of the prion protein. This manifests as a change in metal balance in the brain and other organs and substantial oxidative damage throughout the brain. Thus prions and metals have become tightly linked in the quest to understand the nature of transmissible spongiform encephalopathies.

Accuracy of Four Language Analysis Procedures Performed Automatically

2001 ◽  
Vol 10 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Steven H. Long ◽  
Ron W. Channell
Keyword(s):  
Automatic Identification ◽  
Published Data ◽  
Typically Developing ◽  
Language Impaired ◽  
Productivity Data ◽  
Language Analysis ◽  
Word Classes ◽  
Human Coder ◽  
Impaired Children ◽  
Metalinguistic Skills

Most software for language analysis has relied on an interaction between the metalinguistic skills of a human coder and the calculating ability of the machine to produce reliable results. However, probabilistic parsing algorithms are now capable of highly accurate and completely automatic identification of grammatical word classes. The program Computerized Profiling combines a probabilistic parser with modules customized to produce four clinical grammatical analyses: MLU, LARSP, IPSyn, and DSS. The accuracy of these analyses was assessed on 69 language samples from typically developing, speech-impaired, and language-impaired children, 2 years 6 months to 7 years 10 months. Values obtained with human coding and by the software alone were compared. Results for all four analyses produced automatically were comparable to published data on the manual interrater reliability of these procedures. Clinical decisions based on cutoff scores and productivity data were little affected by the use of automatic rather than human-generated analyses. These findings bode well for future clinical and research use of automatic language analysis software.

Personality of Clown Doctors

2016 ◽  
Vol 37 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Alberto Dionigi
Keyword(s):  
General Population ◽  
Personality Traits ◽  
Big Five ◽  
Normal Population ◽  
Big Five Personality Traits ◽  
Published Data ◽  
Big Five Personality

Abstract. In recent years, both professional and volunteer clowns have become familiar in health settings. The clown represents a peculiar humorist’s character, strictly associated with the performer’s own personality. In this study, the Big Five personality traits (BFI) of 155 Italian clown doctors (130 volunteers and 25 professionals) were compared to published data for the normal population. This study highlighted specific differences between clown doctors and the general population: Clown doctors showed higher agreeableness, conscientiousness, openness, and extraversion, as well as lower neuroticism compared to other people. Moreover, specific differences emerged comparing volunteers and professionals: Professional clowns showed significantly lower in agreeableness compared to their unpaid colleagues. The results are also discussed with reference to previous studies conducted on groups of humorists. Clowns’ personalities showed some peculiarities that can help to explain the facility for their performances in the health setting and that are different than those of other groups of humorists.

ULTRASONIC STUDIES OF THE POLYMER STRUCTURE OF THE CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-955-C4-958
Author(s):  
V. A. Ratobylskaja ◽  
L. A. Simonova
Keyword(s):  
Chalcogenide Glasses ◽  
Polymer Structure

Observations on Cardiac Output and ”Pulmonary Blood Volume” in Normal Man by External Recording of the Intracardiac Flow of 131I Labelled Albumin

1961 ◽  
Vol 1 (04) ◽  
pp. 353-379
Author(s):  
Jacques Lammerant ◽  
Norman Veall ◽  
Michel De Visscher
Keyword(s):  
Cardiac Output ◽  
Blood Volume ◽  
Normal Subjects ◽  
Published Data ◽  
Total Blood Volume ◽  
Total Blood ◽  
Pulmonary Blood Volume ◽  
Intracardiac Flow ◽  
Normal Man ◽  
Mean Circulation

Summary1. The technique for the measurement of cardiac output by external recording of the intracardiac flow of 131I labelled human serum albumin has been extended to provide a measure of the mean circulation time from right to left heart and hence a new approach to the estimation of the pulmonary blood volume.2. Values for the basal cardiac output in normal subjects and its variations with age are in good agreement with the previously published data of other workers.3. The pulmonary blood volume in normal man in the basal state was found to be 28.2 ± 0.6% of the total blood volume.4. There was no correlation between cardiac output and pulmonary blood volume in a series of normal subjects in the basal state.5. The increase in cardiac output during digestion was associated with a decrease in pulmonary blood volume equal to 6.3 ± 1.2% of the total blood volume, that is, about 280 ml.6. The increase in cardiac output during exercise was associated with a decrease in pulmonary blood volume equal to 4.5 ± 1.0% of the total blood volume, that is, about 200 ml.7. The increase in cardiac output attributed to alarm is not associated with a decrease in pulmonary blood volume, the latter may in fact be increased.8. The total blood volume is advocated as a standard of reference for studies of this type in normal subjects in preference to body weight or surface area.9. The significance of these results and the validity of the method are discussed.

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